Walkthroughs for custom maps.

I looked at the save files – it seems like some kind of exploit usage.

No bugs were used, except for boarding a boat without boots/gauntlets with a slow unit. And, of course, at the end, to complete the quest.
But to consider using map features as a bug is questionable.

Added 22 minutes later
In theory, it could have been improved further by launching an attack on Inferno in week 4, but I thought there would be too many losses, which would prevent breaking through the blue rampart for the brown tent later.

Added 10 minutes later

I can't analyze the save files right now, and, to be honest, I'm a little lazy. Could you tell me what the ingenious idea is that no one has figured out yet?

There are 3 ideas.
Rescuing Fata instead of that hellish battle with elementals on day 111 (he is needed later to rescue Kir from the island and Dessa from the cursed land).

Not discarding Armageddon's Blade to unlock the column for further rescuing of Rusty. Moreover, the blade allows you to win the battle against the Azure faction in week 2 and get the Lance of Legend.

Not discarding Dessa when liberating Orin.